1. Technical Field
The present invention relates to dendritic cells pulsed with bisphosphonate-based bone metabolism improving drugs (hereinafter referred to as bisphosphonates). The present invention also relates to pharmaceutical compositions comprising said dendritic cells, therapeutic methods and γδ T-cell culture methods utilizing said dendritic cells.
2. Technical Background
Dendritic cells work as antigen-presenting cells to present antigens, through phagocytosis and fragmentation, as antigenic epitopes on Major Histocompatibility Complex (MHC) molecules at their cell surface. When dendritic cells come in contact with T-cells in a lymph node, the T-cells recognize these antigenic epitopes.
In T-cells, αβ T-cells expressing αβ T-cell receptors and γδ T-cells expressing γδ T-cell receptors are present. The αβ T-cells primarily assume the responsibility for acquired immunity, while the γδ T-cells work as effector cells for immune responses to particular bacterial infections such as tuberculosis, as well as tumors, and mainly assume the responsibility for natural immunity.
It has recently been found that γδ T-cells also have cytotoxic activity against cancer cells, drawing attention to the development of immunotherapy utilizing the powerful antitumor activity possessed by γδ T-cells. The vast majority of T-cells generally present in blood, however, are αβ T-cells; γδ T-cells account for a mere 1-5%. Accordingly, as a method to proliferate γδ T-cells, the γδ T-cells that are separated using magnets and the like are cultured in vitro and returned to the body.
It is known that γδ T-cells are also activated and/or proliferated by nonpeptide antigens; they are known to be activated and/or proliferated by alkaloids such as alkylamines, as well as pyrophosphate monoesters and bisphosphonates.
Above all, methods to cultivate γδ T-cells in vitro utilizing bisphosphonates have been considered in various studies, but failed to produce sufficient numbers of γδ T-cells. An attempt to obtain a sufficient number of γδ T-cells suitable for a treatment meant an increase in the amount of blood collected from a patient, which also increased the burden placed on the patient. Accordingly, there exists a need to establish a technique to easily obtain a sufficient number of γδ T-cells not only in vitro, but also in vivo.